1. Field of the Invention
The present invention is related to the recovery of strong acids from an aqueous solution, and, in particular, to a process, wherein the acid is regained in its anhydrous form from water by a distillation process.
2. Description of the Related Art
Strong acids are employed in the chemical industry as useful catalysts in a large number of hydrocarbon conversion processes. As an example, hydrogen fluoride and sulfuric acids are used in large quantities in the alkylation of hydrocarbons to produce high quality gasoline. Use of perfluorinated sulfonic acids, as catalyst in the alkylation process, has recently been described in the literature.
In order to meet environmental requirements and to improve process economy in a process being catalyzed by a strong acid, it is desirable to recover and to reuse the acid from a process effluent stream containing recoverable quantities of spent acid.
Simple recovery methods would comprise extraction of spent acid into an aqueous phase and subsequent removal of water by distillation or evaporation.
Because of strong interactions between water and the acid, distillation of diluted aqueous solution of the acid, however, results in recovery of the acid in its hydrate form. Acid hydrates are catalytically inactive, and it is, therefore, necessary further to process recovered acid hydrate to its anhydrous form.